Eric's Gizmo tillering tool?

[jeremy1517]

Eric says to use a 1x 1 x 6 piece of wood for his tillering Gizmo.  Can I use a 1 x 2 x 6 for the Gizmo or will adding the extra inch on the width make it not work?

[Roy from Pa]

It will work. Any reason not to cut it in half?

[jeremy1517]

No, just found a scrap that was 1 x 2 x 6.  Figured I would cut it if it was to wide or would work better 1x 1

[Eric Krewson]

I would cut your wood in half to make it 1". The reason is; I often grip my gizmo with my thumb and first finger, centering the 1" wide gizmo on the limb with my finger tips for a quick pass up and down the limb. It would be harder to center the gizmo on the limb if it was 2" wide and your limb is only 1 1/4" like most of my osage bows are.

Here is my latest design, works a little e better than a straight block of wood because it will go further up the limb without string interference.

 

[jeremy1517]

Thanks, so thats your 1 x 1 x 6 block and you tapered it on the side away from the bow limb.

Eric,  when tillering, am I understanding correctly that with each degree of bending your doing in the process, you run your tool down the limb and wherever it leaves a mark you scrape a little off?  You don't bend any farther until you can make your pass without leaving a mark?

How much of the pencil sticks out the marking side?

[tenbrook]

The amount of pencil sticking out depends on how much your limb is bending.  In the beginning stages there will be very little sticking out as you progress you need more pencil.

[Eric Krewson]

Once you determine where the limb is bending the most, you adjust the pencil to about the same distance off the limb as shown in the picture, perhaps not quite as close initially.

   

If your first adjustment marks the whole limb, you have the pencil too close to the limb. Back it off just a little, you only want it to mark the high spots.

[jeremy1517]

Does the Gizmo seem to find most the limb issues thst need corrected?

[Bowjunkie]

I have a question about using the Gizmo... is it used on selfbows that show any degree of humps, dips, or undulations unbraced? If so, how? Or is it used only on board bows and equally straight-standing stave bows?

That's my biggest concern with it... it would seem to lend folks to tillering bows for a perfect arc, even when that's not the appropriate tiller shape for staves that are less than perfectly straight. Same concerns with d/r bows too I guess. Just something I've been wondering, and I've never heard it addressed.

[Eric Krewson]

The gizmo doesn't work on roller coaster staves.

Here is the biggest misconception about the gizmo, that it is the end all be all for a great shooting bow, not so.

The main reason I developed the gizmo it to allow a smooth transition from floor tillering, to long string and then to the short string with no hinges, weak limbs or most of all, coming in way under poundage. You won't be removing a bunch of excess wood that you can't put back while you chase tiller, just what wood you actually need to get the limbs bending evenly.

If you use the gizmo correctly you should get to the short string at least 20# over your target weight. From there you have plenty of room to change the tillering configuration to any style you choose.

[Roy from Pa]

Jeff, it's no different than that credit card you use when tillering your bows:)

[jeremy1517]

I figured it wasn't the magic tool for tillering. Do you use a scraper to lightly remove wood at the marked area and continue checking until no marks appear?

[Bowjunkie]

Roy, I haven't used a credit card or any straight edge to tiller in years.I mostly did it for your benefit anyhow... They're just training tools used til ya aquire your tillerin eye.

[Eric Krewson]

Ten scrapes to remove a pencil marks, flex and recheck, ten scrapes and so forth, probably take 5 or 6 scrape and check sessions to see much movement. The pencil marks will get shorter and shorter until they disappear.